The Problem

The Van Tulder property had an aging railroad tie retaining wall that had begun to fail, posing a serious threat to the surrounding landscape—including a large, mature cedar tree the homeowners wanted to preserve. The hillside was actively shifting, increasing the risk of erosion, property damage, and tree loss. The area also lacked proper drainage, compounding the issue with stormwater runoff.

The Solution

To permanently stabilize the slope and protect the cedar tree, Sejant Northwest executed a full-scale hillside remediation plan. This included:

• Excavation of the upper hillside to safely create working space around the tree.

• Installation of 37 two-inch pin piles (2″ steel pipes with ¼” wall thickness), driven between 10–20 feet deep to anchor the new retaining wall.

• Shotcrete retaining wall: A new 8″ thick shotcrete wall was formed over a rebar grid (No. 4 and No. 5 bars, spaced 12″ on center both directions) for superior strength and durability.

• Helical tiebacks: 18 heavy-duty helical anchors (2-7/8″ round shaft, 8″, 10″, and 12″ helix blades) were drilled 25 feet deep into the hillside to lock the wall into stable soil per the engineer’s specifications.

• Drainage system installed behind the wall to redirect stormwater and prevent future saturation-related movement.

• Custom concrete stairway built alongside the wall to improve access to the hillside.

All work was done to meet strict engineering standards, including testing the tiebacks for holding strength as required by the structural design.

The Results

The Van Tulder family gained a reinforced, permanent retaining wall that stopped hillside movement in its tracks—ensuring long-term safety for their property and preserving the beloved cedar tree. The new system not only protects against erosion and landslide risk but also enhanced the usability and appearance of the space, allowing for future gardening and landscaping projects with confidence.